Many electronic devices require a precision current for proper operation. For example, multi-meters require a precision current from measuring resistance and capacitance values. In both cases, the current is sourced into a device under test (DUT) and voltage is measured across it. When the voltage and current are known (as well as time for a capacitor), the value of the resistance or capacitance can be calculated. However, the current must be precisely maintained in order for results to be accurate and consistent.
In order to assure a precision current, precision components may be added to the electronic circuit. In the case of a multi-meter, for example, numerous additional precision resistors and at least one precision operational amplifier (OpAmp) and a switch may be added to the circuit to provide a precision current, e.g., to the DUT. However, such additional components are expensive and occupy additional board space, adding cost and size to the end product. In addition, they may inhibit achieving complete accuracy.